dln_find.c: unused macros

* dln_find.c: remove unused macros.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41031 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
dln_find.c: deprecated functions

* dln_find.c (dln_find_exe, dln_find_file): remove deprecated
  non-reentrant functions.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41032 b2dd03c8-39d4-4d8f-98ff-823fe69b080e